TWI479027B - Hard alloy - Google Patents

Description

Superhard alloy

The present invention relates to superhard alloys and processing tools using the same. In particular, a superhard alloy that exhibits superior strength when used in a cutting tool or a wear-resistant member.

In the past, a superhard alloy having a WC of an average particle diameter of 1 μm or less as a hard phase, that is, a so-called micro-hard alloy, is known as a material having excellent strength or wear resistance (for example, see Patent Document 1). In the superhard alloy, WC is used as a fine particle, and it is generally used as a WC raw material powder as a material. However, even in the case of a superhard alloy made of a WC raw material powder using fine particles, there is a sudden breakage or a cut due to the use of the tool composed of the super hard alloy. For this reason, it is known that the hardness is increased by making the WC particle size which becomes a hard phase extremely small, and the hard toughness with an exchange relationship is lowered. Further, as another reason, there is a large WC in which the grain observed by the microscope cross-sectional structure is grown to 2 μm or more. This large WC is likely to be a starting point for destruction, and the alloy characteristics, the cutting characteristics or the wear resistance when it becomes a tool are remarkably lowered. The super-hard alloy is usually sintered in the liquid phase, and the bonded phase will become a liquid phase during sintering, and the hard phase which is solid-dissolved and diffused in the liquid phase will be precipitated into a large WC in the cooling process, causing the so-called Oswald growth. The grain grows. This grain growth is particularly difficult to suppress when using an ultrafine particle raw material powder of less than 1 μm, and is related to the unevenness of fine structure. Here, it is reviewed that a grain growth inhibitor of V, Cr, and Ta having a large particle growth inhibitory effect is added to the alloy composition, and the grain growth of WC is suppressed (see Patent Document 2).

Patent Document 1: JP-A-61-195951, Patent Document 2: JP-A-2001-115229

The addition of V, Cr, and Ta suppresses the grain growth of WC, and the average particle diameter can be made fine. However, it is difficult to completely suppress the growth of the large particles by merely adding the particle growth inhibitors. Therefore, in addition to uniformization and miniaturization, it is desirable to reduce the large particles which are the origin of the destruction or the incision.

On the other hand, when the WC system in the superhard alloy is finer, it tends to increase hardness and strength. Here, in order to improve hardness and strength, the WC in the superhard alloy is made finer, and it is specifically considered to be an average particle diameter of 0.3 μm or less, and a finer WC raw material powder is used. However, when such an ultrafine raw material powder is used, it is easy to cause the above-mentioned grain growth, and it is easy to generate a large particle which becomes a defect.

Here, the main object of the present invention is to provide a super-hard alloy which has a uniform WC and a small WC number, and is excellent in both strength and toughness. Further, another object of the present invention is to provide a processing tool using the super hard alloy.

In order to achieve the above object, the inventors of the present invention have reviewed the use of a finer material as a material powder to achieve a finer alloy structure. In a superhard alloy in which the hard phase is fine particles, it is generally considered that the smaller the WC particle size, the higher the strength (for example, the bending resistance). However, when a fine material powder is used to obtain ultrafine particles WC of 1 μm or less, WC causes the particles to grow to cause a decrease in strength. Here, as a result of reviewing the relationship between the various particle growth inhibitors for suppressing the growth of WC particles and the relationship between the combination and the amount of the bound phase, it was found that even the elements used as the particle growth inhibitor of WC in the past (specifically In the case of Ta), the phase containing the element grows, which will become a defect. Further, it has been found that even if an element which is a particle growth inhibitor (specifically Ti) is hardly utilized in the past, it is very effective to suppress the growth of WC by adding a specific amount. It has also been found that the element has a correlation with the elements of the binding phase, and in the growth inhibition of the WC, it is necessary to contain a specific amount of the element and also a specific amount of the element of the binding phase. Further, it has been found that the content of an element (specifically, Cr) used as a particle growth inhibitor in the past is preferably controlled so as to have a specific relationship with the amount of bound phase. Based on these findings, the present invention defines the average particle size of WC as a hard phase. Further, as an element for promoting the refinement of the WC which becomes a hard phase, it is prescribed to contain Cr and Ti, and the content of Ti, the relationship between Cr and the amount of bonded phase, and the content of the binder phase are defined.

That is, the superhard alloy of the present invention is characterized in that WC having an average particle diameter of 0.3 μm or less is used as a hard phase; at least one iron group metal element having a mass % of 5.5% to 15% is used as a binder phase; 0.005% to 0.06% includes Ti; and the weight ratio to the binder phase is 0.04 or more and 0.2 or less, and Cr is contained; the residue is composed of unavoidable impurities. In particular, the Ta content is % by mass less than 0.005%. Hereinafter, the present invention will be described in more detail.

The superhard alloy of the present invention has a WC as a hard phase and a sintered metal such as a group metal element such as Co, Ni or Fe as a binder phase. In particular, the average particle diameter of the hard phase (WC) in the sintered body is 0.3 μm or less. When the WC average particle diameter exceeds 0.3 μm, the hardness (wear resistance) is lowered and the strength (flexibility) is lowered. A more preferable average particle diameter is 0.1 μm or less. Although the WC average particle size can be increased in hardness and strength due to the smaller size, the lower limit is not particularly set, but there is a limit in consideration of the actual manufacturing process. The WC average particle diameter is observed by microscopic observation (for example, 8000 to 10000 times by SEM (scanning electron microscope)), using the Fullman formula (dm = 4N _L / π N _S , dm: average particle size, N _L : The number of hard phases (WC) per unit length in any straight line on the microscope surface, N _S : the number of hard phases (WC) present per unit area on the microscope surface). The measurement length was arbitrary, and finally the particle size per unit length (1 μm) was calculated. In addition, the surface of the superhard alloy is observed at a high magnification (for example, 8000 to 10000 times) in the SEM, and the observed image is read to a computer, and analyzed by an image analyzing device to determine a range of a certain area (for example, 20 to 30 mm ² ). The WC particle diameter (μm) present in the medium may be appropriately corrected by the Fourman formula. In the product of the present invention, since the particle size of the hard phase in the sintered body is extremely small, even if the unit area is in a small range of 1 μm ² , it can be judged that the particle diameter can be sufficiently measured. In the conventional tissue control method, it is difficult to make the WC average particle diameter in the sintered body ultrafine to 0.3 μm or less. In the present invention, in addition to the addition control of the addition of a trace amount of Ti and Cr as described later, Ta is not contained, and an average particle diameter of 0.3 μm or less is achieved. Further, the WC powder which is a raw material is also reduced in size due to the increase in grain growth, and it is preferable to use a smaller average particle diameter.

The superhard alloy of the present invention contains at least one element selected from the group consisting of iron metals as a binding phase. In particular, Co is preferred, and although Co may be used as the binder phase, a part thereof may be substituted with Ni. The content of the binder phase (the total content when the elements constituting the binder phase are plural elements) is 5.5% by mass or more and 15% by mass or less. When it is less than 5.5% by mass, the flexural strength is lowered even if Ti or Cr is appropriately contained as described later. When it exceeds 15% by mass, W (tungsten) will be solid-dissolved in a large amount in the binder phase due to too much binder phase, and the consideration will cause re-epitaxial appearance. Therefore, it is difficult to reduce the frequency of occurrence of a large hard phase (WC), and the effect of reducing the existence of a large hard phase is small. More preferably, the combined phase content is 7.0% by mass or more and 12.0% by mass or less.

In the superhard alloy of the present invention, Cr is used as a grain growth inhibitor in order to suppress the growth of WC particles in the alloy structure. In particular, the Cr content is a specific ratio with respect to the weight (% by mass) of the iron group metal element as the above-mentioned binder phase. Specifically, the weight ratio of Cr to the bonded phase is made 0.04 or more and 0.2 or less. When the weight ratio is 0.04 or more, the synergistic effect caused by coexistence with a very small amount of Ti, which will be described later, is preferable because the effect of suppressing the grain growth is large. However, when the weight is 0.2, the brittle phase (for example, carbide of Cr) is precipitated in the alloy structure due to excessive Cr, and the precipitate is likely to be used as a starting point to cause a decrease in strength. More preferably, the Cr weight ratio is 0.08 or more and 0.14 or less.

In addition to the above Cr, in the present invention, Ti is contained in an extremely small amount, specifically, 0.005 mass% or more and 0.06 mass% or less. The Ti-based grain growth inhibiting effect is small, and in the prior art, Ti is hardly added for the purpose of performing tissue control. However, when the inventors reviewed and controlled the WC to ultrafine particles of 0.3 μm or less, it was found that a very small amount of Ti contributes greatly to the grain growth control of WC. In this case, the inventors of the present invention have found that not only the amount of Ti is extremely small, but also the content of the iron group metal element which is incorporated into the binder phase as described above, and specifically, when the binder phase is contained in an amount of 5.5% by mass or more, the growth of the pellet can be expected. The flexural strength of the inhibitory effect. When Ti is added in a trace amount as a combination of a superhard alloy, there is an effect that the wettability of the element which becomes a binder phase and WC deteriorates somewhat. Therefore, it is considered that the WC diffusion inhibits solid solution in the binding phase when the liquid phase appears, and inhibits the Oswald growth of WC. Here, the content of the specific Ti and the content of the binder phase in the present invention. When the content of Ti is less than 0.005% by mass, the content of impurities is a content of impurities, and the effect of suppressing grain growth is small. When it exceeds 0.06 mass%, the strength will fall. A particularly preferable Ti content is 0.01% by mass or more and 0.04% by mass or less. In the present invention, the addition of Ti in addition to Cr in this manner makes WC uniform and fine, and suppresses the generation of large particles exceeding 2 μm as much as possible, and has a preferable folding resistance. Further, the content of each component can be determined, for example, by ICP (inductively coupled plasma luminescence analysis) analysis.

Thereafter, in the superhard alloy of the present invention, the Ta content is made less than 0.005 mass%. In the present invention, Ta is intentionally not contained. Therefore, in the present invention, Ta is not contained, that is, the content of Ta is preferably 0, and in consideration of unavoidable mixing, it is preferably 0.003 mass% or less, and the upper limit is 0.005 mass%. In the past, it has been known that the Ta system is actively added as a particle growth inhibitor. However, as a result of review by the inventors of the present invention, it has been found that the addition of Ta is particularly preferable because the WC is controlled to be ultrafine particles of 0.3 μm or less. Specifically, it is known that a carbide containing a complex carbide phase of Ta ((W, Ta) C) or Ta is generated in liquid phase sintering, and the hard phase is greatly grown. Then, it is found that even if an element such as Ti or Cr is added to the precipitate containing Ta, it is difficult to suppress the grain growth and to refine it. Here, in the present invention, Ta is not contained.

Further, by adding a specific amount of V (vanadium), it is possible to more effectively suppress the grain growth and to make the fineness stable, which is preferable. Specifically, V is contained so that the ratio (weight ratio) of V weight (% by mass) of the weight (% by mass) of the iron group metal element as the binder phase is 0.01 or more and 0.1 or less. When the weight is compared with 0.01, the stability of the particle structure will be insufficient, and the effect of adding V cannot be sufficiently obtained. When the weight ratio of 0.1 is large, the wettability of the hard phase and the binder phase is deteriorated, and the fracture toughness tends to be lowered. A particularly preferable weight ratio is 0.01 or more and 0.06 or less.

When the above-mentioned superhard alloy having an ultrafine particle having a WC of 0.3 μm or less is produced, preparation of a material powder → mixing and pulverization of a material powder, die casting, sintering, and hot press molding (HIP) can be exemplified. The WC powder in the material powder is ultrafine particles, and specifically, it is preferably 0.5 μm or less, particularly preferably 0.2 μm or less. The ultrafine particle WC powder is obtained by direct carbonization of tungsten oxide to adjust the WC to fine and uniform particles. Further, the WC particles can be made smaller by mixing the pulverized material powder. In addition to the WC powder, a powder containing an iron group metal powder to be a binder phase, Cr, Ti, and an appropriate amount of V for the purpose of suppressing grain growth is prepared. Cr, Ti, and V may be added in the form of any one of a metal monomer, a compound, a composite compound, and a solid solution. The compound or the composite compound may, for example, be one selected from the group consisting of carbon, nitrogen, oxygen, and boron and the above-mentioned elements Cr, Ti, and V. It is also possible to use powder that is sold in the market. The powder may be further mixed and pulverized by mixing the powders in advance, and each of the powders may be separately mixed during mixing and pulverization. Here, the adjustment of the Ti content may be performed by measurement. For example, when mixing by a ball mill, the ball to which the Ti film is applied may be used by adjusting the mixing time. The above-mentioned mixed pulverized material is die-casted at a specific pressure, for example, 500 to 2000 kg/cm ² , and sintered in a vacuum. The sintering temperature is preferably a low temperature in order to suppress the grain growth of WC. Specifically, 1300~1350 °C is preferred. Thereafter, in the present invention, the properties such as hardness, flexural strength, and toughness are further improved, and HIP is applied after sintering. The specific HIP condition is such that the temperature is about the same as the sintering temperature (1300 to 1350 ° C), and the pressure is preferably 10 to 100 MPa, particularly about 100 Mpa (1000 atmospheres). By performing such a HIP treatment, even if it is sintered at a low temperature, it can be a superhard alloy having the above characteristics.

The above-mentioned superhard alloy of the present invention is suitable for use as a base material for a processing tool such as a cutting tool or a wear-resistant tool. Examples of the cutting tool include a rotary tool such as a drill, an end mill, a milling machine, and a reamer; a rotary tool for printing a substrate such as a micro drill; a rotary machining such as aluminum or cast iron, and the like, and a multi-blade blade for performing processing, etc. Tools for turning. In addition, the need for sharp electrical. It can also be used in high-precision machining applications such as electronic equipment. As the wear-resistant tool, a cutting tool such as a rotary blade or a through tool such as a casting mold can be used. The superhard alloy of the present invention is used for the processing tool of the entire base material, because not only the part of the base material, but also the large WC is reduced in the whole, so the starting point of the damage is small, and the fracture resistance and the cut resistance can be expected to be improved by The WC across the entire base material is evenly refined, and the strength can be expected to be improved, so that good processing performance can be exhibited.

The micro-bit is used as a tool for printing the opening of a substrate, and the diameter of the drill: the extremely small diameter of φ 0.1 to 0.3 mm is gradually becoming the mainstream. When such an extremely small diameter is used, if the alloy structure of the entire base material is not fine and homogeneous, it is likely to cause damage or breakage as a starting point of a large hard phase in the structure. Therefore, when the particulate superhard alloy of the present invention is used as a base material of a micro drill, the performance of the superhard alloy of the present invention can be utilized, and good cutting performance can be expected in the past. Further, the superhard alloy of the present invention is not only excellent in abrasion resistance, but also excellent in strength and toughness. Therefore, even a material such as a stainless steel plate in which a micro drill bit is broken in the past can be subjected to drilling. Further, when the superhard alloy of the present invention is used, an ultrafine drill having a drill diameter of φ 0.05 mm (50 μm) can be produced.

The use of the tool for the turning of the cemented carbide of the present invention can be expected to improve the resistance to the curling edge by preventing the sudden edge of the blade, and the wear resistance of the high hardness can be expected to be improved, so that the cutting performance is excellent.

The above-mentioned superhard alloy of the present invention contains Ti which is hardly used as a particle growth inhibitor in the past, and does not contain Ta which is used as a grain growth inhibitor. After that, the superhard alloy of the present invention can effectively suppress the grain growth of the hard phase by the content of the specific binder phase, the content of Cr, and the content of Ti, thereby achieving uniform miniaturization of the hard phase and reducing the number of large particles. effect. Therefore, in various processing tools using the superhard alloy of the present invention, sudden breakage or nicking due to the presence of a large hard phase in the alloy structure can be suppressed, and the strength is increased by uniform miniaturization of the hard phase, so that high strength Stand tall with high toughness. Therefore, the cemented carbide of the present invention is useful in various processing fields such as rotary cutting, precision machining, turning, and processing requiring abrasion resistance.

[Best Mode for Carrying Out the Invention]

Embodiments of the present invention will be described below.

(Example 1)

Prepare a WC raw material powder having an average particle diameter of 0.5 μm, a Co raw material powder having an average particle diameter of 1 μm, a compound powder of Cr, V, Ti, Ta in the combination shown in Table 1, and an appropriate amount of powder C (carbon), respectively. The addition amount (mass% = mass%) shown in 1 was added, and the mixture was pulverized and mixed in a ball mill for 48 hours. Then, it was dried and granulated using a jet dryer, and then die-cast at a pressure of 1000 kg/cm ² , heated to a sintering temperature of 1,350 ° C in a vacuum, and sintered at the sintering temperature for 1 hour. Thereafter, HIP treatment was carried out at 1320 ° C, 100 MPa, and 1 hour to prepare a superhard alloy of samples No. 1 to 27. Here, a JIS test piece, a Vickers hardness Hv evaluation sample, a tissue observation sample, and a component measurement sample each having a 20 mm span were prepared for each sample.

In addition, in the same combination as sample No. 6, an attempt was made to produce a WC having an average particle diameter difference (Sample No. 50), Ni as a part of Co (Sample No. 51), and a premixed material powder ( Sample No. 52) and those who did not perform HIP (Sample No. 53). The sample 50 was prepared by preparing a WC raw material powder having an average particle diameter of 1.0 μm, a Co raw material powder having an average particle diameter of 1 μm, a compound powder of Cr and Ti shown in Table 1, and an appropriate amount of powder C, as shown in Table 1. The addition amount was added, and the mixture was pulverized and mixed in a ball mill for 24 hours, and then dried, granulated, and die-cast in the same manner as above, and sintered at 1400 ° C as a sintering temperature. Sample No. 51 was produced under the same conditions as the above-mentioned sample Nos. 1 to 27 except that the Ni raw material powder having an average particle diameter of 1 μm and the Co raw material powder were used. Sample No. 52 was produced under the same conditions as the above-mentioned sample Nos. 1 to 27, except that the material powder of the combination shown in Table 1 was used in advance. In the sample No. 53, the material powders of the combination shown in Table 1 were prepared, and the addition amount was added in the amount shown in Table 1, and the mixture was pulverized and mixed in a ball mill for 24 hours, and then dried, granulated, and die-cast in the same manner as above. 1450 ° C is obtained by sintering at a sintering temperature.

For the contents of Cr, Ti, Ta, and V in each sample obtained by the investigation, samples for component measurement were used, and analyzed by ICP, and the weight ratio of Cr to mass (mass%) of the bonded phase (Co or Co+Ni) was determined. Ratio to V weight. Table 1 shows the analytical value of Ti, the weight ratio of Cr to Co, and the weight ratio of V to Co. Further, in the sample in which VC or TaC was not added (described as "- (horizontal line) in Table 1), V or Ta was not detected.

Using the sample for tissue observation, the average particle diameter (μm) of the hard phase (WC) in the alloy was determined by the Fuman formula from the observation of the structure. The observation system was carried out by SEM (3000 times), and the unit length and unit area were 1 μm and 1 μm ² , respectively. Further, the Vickers hardness Hv was measured using a Vickers hardness Hv evaluation sample. Further, the JIS test piece was used for the bending resistance test, and an attempt was made to determine the bending resistance. In the test, the bending resistance of each of 10 samples was measured, and the average value of the bending resistance (GPa) of 10 pieces and the lowest value (GPa) of 10 pieces were determined. In the evaluation of the bending strength test, the greater the difference between the average value and the minimum value, the greater the dispersibility of the bending resistance, and it can be said that there is a large hard phase in the tissue which is likely to be the starting point of the break or the slit. These results are shown in Table 2.

As shown in Table 2, samples No. 4-7, 10-11, 15-18, 23-27 containing a specific amount of iron group metal as a binder phase and containing a very small amount of Ti, and containing a specific amount of Cr for the binder phase. 51 and 52, it was found that the WC average particle diameter was fine and 0.3 μm or less, and the hardness was high. Further, it was found that the average value of the average bending strength of the samples was high, and the dispersion of the bending resistance was small. Generally, the particle size of the hard phase becomes small, and the hardness is increased but the reverse side tends to have a reduced bending force. However, in samples No. 4-7, 10-11, 15-18, 23-27, 51, and 52, both hardness and flexural strength were found to be good. Particularly, in the sample No. 23-27 containing a specific amount of V, it was found that the bending resistance was better and the hardness was high.

By comparing sample Nos. 1 to 8, it was found that the combined phase content would affect the strength. By comparing Sample Nos. 6 and 9 to 13, it was found that the content of Ti affects the grain growth inhibition of WC. By comparing Sample Nos. 6 and 14 to 19, it was found that the Cr content would affect the dispersion of the bending resistance. Sample No. 14 or Sample No. 19 had a large dispersibility due to the folding force, and there was a large hard phase which was considered to be a breakage or a starting point of the slit. That is, it is known that the Cr content contributes to the suppression of grain growth of WC. By comparing samples No. 6 and 20 to 23, it was found that the presence or absence of Ta would affect the suppression of grain growth of WC.

By comparing Sample Nos. 6 and 50, it was found that a finer WC can be obtained by using a finer particle as a raw material powder, and a high-strength and high-hardness superhard alloy can be obtained. By comparing Sample Nos. 6 and 51, it was found that when the bonded phase became only Co, a superhard alloy having better characteristics was obtained. By comparing Sample Nos. 6 and 52, it was found that various material powders can be utilized. By comparing Sample Nos. 6 and 53, it was found that a fine superhard alloy having preferable characteristics can be obtained by low-temperature sintering and HIP treatment.

(Example 2)

A raw material powder of the same combination as Sample Nos. 1 to 27 of Example 1 was used to prepare a micro drill having a diameter of 0.3 mm. The micro drill was pulverized and mixed in the same manner as in Example 1, and then dried and granulated, and die-cast into a round bar of Φ 3.5 mm, sintered at 1350 ° C, and subjected to HIP treatment at 1320 ° C to perform peripheral processing (groove processing). And making.

The opening test (through hole) was performed by the micro drill produced, and the cutting evaluation was performed. The material to be cut is a combination of a printed circuit board (thickness 1.6 mm) composed of a four-layer laminated board (a copper-clad laminate grade: FR-4 specified by the American Society for Standardization). The total thickness is 3.2 mm), the cutting conditions are the number of rotations N = 150,000 rpm, the conveying amount is f = 15 μm/rev., and the cutting oil (dry type) is not used. The cutting evaluation is performed to the number of drilling operations up to the breakage. The results are shown in Table 3.

As shown in Table 3, samples No. 4-7, 10-11, 15-18, 23-27 containing a specific amount of iron group metal as a binder phase, containing a trace amount of Ti, and containing a specific amount of Cr for the binder phase were known. The micro-bits formed are less likely to be broken, and the fracture resistance is better, that is, the toughness is better. As a result of this kind of measurement, it is presumed that there is almost no large WC in the micro-bits. Therefore, the cutting tool composed of the superhard alloy of the present invention has better nick resistance and can improve tool life.

(Example 3)

Using a raw material powder of the same combination as Sample Nos. 1 to 27 of Example 1, a multi-blade insert of a TNGG 160404R-UM chipbreaker was produced under the same conditions, and a cutting test was performed to perform cutting evaluation. The material to be cut is aluminum (ADC12). The cutting conditions are cutting speed V=500 m/min, conveying amount f=0.1 mm/rev., cutting depth d=1.0 mm, and cutting oil (wet). The cutting evaluation was performed by the side wear amount (V _B wear amount) after the 15-hour cutting. As a result, a blade having a specific amount of an iron group metal as a binder phase, containing a trace amount of Ti, and containing a specific amount of Cr in the binder phase, Nos. 4-7, 10-11, 15-18, and 23-27, It was confirmed that the wear was less and the strength was better. As a result of this, it is presumed that the hard phases of the blades are uniformly fined. Therefore, the cutting tool composed of the superhard alloy of the present invention has better wear resistance and can improve tool life.

(Example 4)

Using the raw material powders of the same combination as the sample Nos. 1 to 27 of the first embodiment, a penetration mold was produced under the same conditions, and an abrasion resistance test was performed to evaluate the abrasion resistance. The test was carried out by measuring the diameter of the perforating machine: 1.0 mm through a stainless steel plate having a thickness of 0.2 mm, and then passing through a specific number to evaluate the amount of wear of the mold. As a result, a mold having a specific amount of an iron group metal as a binder phase and containing a trace amount of Ti and containing a specific amount of Cr in the binder phase No. 4-7, 10-11, 15-18, and 23-27, It is confirmed that there is less wear and better strength.

Industrial use possibility

The superhard alloy of the present invention is suitable for various tool materials which are expected to have excellent wear resistance, strength and toughness. Specifically, it can be applied to a cutting tool such as a rotary tool, a rotary tool for printing a substrate, a tool for a turning tool, a tool for cutting, a tool for penetration, or a wear-resistant tool. In particular, it is particularly suitable for a micromachining tool such as an electronic device such as a micro-drill which is used for a hole in a printed circuit board, and a tool material for microfabrication, such as a tool for machining a part used in micromachining. Furthermore, the processing tool of the present invention is suitable for use in cutting or wear-resistant processing.

Claims (3)

A superhard alloy for the manufacture of a micro drill bit for a processing tool, characterized in that WC having an average particle diameter of 0.3 μm or less is used as a hard phase; and at least one iron group metal element having a mass % of 5.5% to 15% As the binder phase, Ti is contained in a mass % of 0.005% to 0.06%; in a weight ratio of 0.04 or more to 0.2 or less, Cr is contained; substantially no Ta is contained; and the residue is composed of unavoidable impurities. The superhard alloy of claim 1, wherein the bonding phase is only Co. The superhard alloy of claim 1 or 2, wherein V is further contained in a weight ratio of 0.01 or more to 0.1 or less for the binder phase.